Results of experimental investigations of the energetic and temporal pumping and lasing characteristics of pulsed gas-discharge excimer ArF (193 nm) and KrF (248 nm) lasers with He as a buffer gas are presented. The parameters of a modified high-voltage exciting circuit of LC-inverter type with automatic preionization have been optimized with the use of RU-65 spark-gap switch. Lasing efficiency of 1.5% has been obtained for the active medium He:Ar:F2 in ratios 79.7:20:0.3 at a total pressure of 2.2 atm for an output energy of 360 mJ. The maximum output energy for the ArF laser was 550 mJ for efficiency of 1.4%, 12-ns pulse duration at half maximum, and an output energy density of 4 J/l. The efficiency of the KrF laser with the active medium He:Kr:F2 in ratios 89.8:10:0.2 at a total pressure of 2.5 atm was 2.4% for an output energy of 570 mJ. The maximum output energy for the KrF laser was 820 mJ for efficiency of 2.0%, 24-ns pulse duration at half maximum, and an output energy density of 5.9 J/l.